Inflatable therapeutic supports for bedridden patients have been well known for many years. Such therapeutic supports include inflatable mattresses and cushions.
Most therapeutic mattresses are designed to reduce "interface pressures", which are the pressures encountered between the mattress and the skin of a patient lying on the mattress. It is well known that interface pressures can significantly affect the well-being of immobile patients in that higher interface pressures can reduce local blood circulation, tending to cause bed sores and other complications. With inflatable mattresses, such interface pressures depend (in part) on the air pressure within the inflatable support cushions.
Rotating the patient on an inflatable mattress is also a well known method to avoid bed sores on immobile patients. Such a method is disclosed in U.S. Pat. No. 5,794,289 which is commonly assigned and is hereby incorporated by reference.
U.S. Pat. No. 5,794,289 describes a mattress unit having a plurality of air cells. The mattress unit rotates a patient by controlling the air pressure in each air cell by inflation and deflation. To rotate a patient to its right side requires deflating the right air cells and inflating the left air cells. The air pressure required to rotate the patient depends on the patient's weight, body type and various other parameters.
The quantity of air pressure that rotates one patient, e.g., 30 degrees may rotate another patient, e.g., 5 degrees. For example, two female patients weigh 130 pounds, one patient is pear-shaped and the other is apple-shaped. The pear-shaped patient rotates 15 degrees with 10 mm Hg while an apple-shaped patient rotates 7 degrees with 10 mm Hg. Obviously each patient is unique and different. Therefore, the programming that controls the air pressure in each mattress unit must be altered to comply with each patient.
Programming an air pressure mattress unit requires a skilled technician. The skilled technician analyzes each patient and alters the programming to attain the desired rotation and air pressure. One means to avoid the expensive technician's analysis and re-programming is to create a self-monitoring mattress.
Previous self-monitoring air pressure mattresses have utilized electrical signal transmission devices and electrical signal receiving devices that sandwich the top and bottom of each bladder to monitor the bladder size. The bladder size corresponds to the desired rotation and air pressure. Such signal devices are disclosed in U.S. Pat. No. 5,794,289. Those signal devices generate electrical signals, like rf signals, that may adversely affect other medical equipment. Thus, there is a need to have a self-monitoring air volume mattress that monitors the bladder size to determine when the desired rotation and loft of the mattress is attained for any patient type without causing any possible adverse effect on other medical equipment.
It is another object of the present invention to make the mattress easy to use for an untrained user.
"Bottoming" refers to any state where the upper surface of any given cushion is depressed to a point that it contacts the lower surface, thereby markedly increasing the interface pressure where the two surfaces contact each other.
There has also been a long-felt need to have an inflatable mattress which maintains a desired air volume within the inflated cushion or cushions to prevent bottoming.